In the case where no shield exists between a mobile station travelling at high speed and a base station, the propagation environment of radio waves is a so-called Rician fading environment. In this case, it is known that the influence of the Doppler Effect on a reception signal appears as a frequency deviation, which greatly affects the communication quality (see, for example, 3GPP (Third Generation Partnership Project) Contribution, R4-060149, “Discussion on AFC problem under high speed train environment”, NTT DoCoMo, USA, Feb. 13-17, 2006). As a method for estimating the frequency of a reception signal, a method for estimating the phase rotation at reception intervals by calculating the correlation between reference signals received at different reception times is known (see, for example, P. Moose, “A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction”, IEEE Trans. Commun., vol. 42, no. 10, October. 1994).
Furthermore, a method is known in which in the case where a plurality of temporally separate reference signals are arranged in an information transmission unit received from a mobile station, a base station calculates a phase change on the basis of the plurality of reference signals and calculates a frequency deviation on the basis of the phase change (see, for example, Japanese Laid-open Patent Publication No. 2009-065581). Furthermore, a method for estimating a frequency deviation on the basis of the phase deviation and time interval between a known symbol inserted in a common control channel and a synchronization code is available (see, for example, Japanese Laid-open Patent Publication No. 2007-515109).
Furthermore, a method for calculating a first phase difference on the basis of a phase variation component between a plurality of pilot symbols arranged within one slot, calculating a second phase difference on the basis of a phase variation component between pilot symbol groups in two slots, and detecting a frequency deviation using the first phase difference and the second phase difference is available (see, for example, Japanese Laid-open Patent Publication No. 2004-153585). Furthermore, a method for calculating, for individual channels, estimate values of differences between the frequency of a receiving signal and its own operating frequency on the basis of pilot symbols of a plurality of channels and controlling the operating frequency on the basis of the calculated estimated values is available (see, for example, Japanese Laid-open Patent Publication No. 2001-086031).
A mobile station being traveling receives from a base station a downlink signal including Doppler frequency added thereto as a frequency deviation, and determines the carrier frequency of an uplink signal to the base station on the basis of the carrier frequency of the reception signal. Meanwhile, the base station receives from the mobile station being travelling an uplink signal including Doppler frequency added thereto as a frequency deviation. Thus, the uplink signal received by the base station may have a frequency deviation twice the Doppler frequency.